In general, a tire is provided with tread grooves for drainage to thereby improve wet grip performance. Such a water-draining function is very important under high speed running, and the recent high-performance cars require a further improved wet grip performance.
However, the tread grooves make noise, and means of improving the wet grip performance generally increase noise level.
To solve those contradictory problems, in Japanese Patent Application Jr-A-02-14905, a block pattern is disclosed, wherein the tread is provided in the ground contacting area with straight grooves inclined at an acute angle of 15 to 40 degrees with respect to the circumferential direction of the tire. However, due to the small inclination angle, the tread rigidity is low, and steering stability is not good, and further wet grip is low.